The present invention relates to rebar cage assemblies for use in reinforced concrete structures, and more particularly relates to a system of engineered internal supports for supporting a rebar cage.
Concrete structures, such as columns and the like, are typically constructed with a steel bar (rebar) cage. The rebar cage is generally cylindrical in shape with circular spacer members that support transversely running steel bars. The particular specifications and dimensions of a given rebar cage can depend on any number of factors, including, e.g., the size of the concrete structure being built, the engineering requirements, soil conditions, wind loads, etc. Based on developments in excavating and drilling equipment, it is no longer unusual for a cage to be 60 or more feet long, ten or so feet in diameter, and weigh tens of thousands of pounds. U.S. Pat. No. 4,467,583 issued to Hasak on Aug. 28, 1984, which is hereby incorporated by reference, describes such a structure (referred to therein as a “basket”).
In a typical application, the rebar cage is custom fabricated off-premises and then transported to the construction site. Because of the height, weight and size, most rebar cages are manufactured and transported lying on their sides. At the time of installation, the cage is brought upright, or “tripped” and then placed in position, e.g., in a form or a drilled shaft, after which concrete is placed to create the reinforced concrete structure.
One of the challenges in manufacturing rebar cages is to ensure structural and dimensional stability is maintained while the cage is being transported, tripped, and set in place. A poorly fabricated or inadequately supported cage can become unstable under its own weight and collapse on itself, resulting in significant losses in time and money. Further, inaccurate or uncertain placement of components can result in structural capacity less than that required by codes or designers.